The worst of China's coronavirus outbreak might be fading away, but monitoring apps that were being used to identify people who could be spreading the illness might remain a permanent fixture on citizens' smartphones because few limits have been set on how the gathered data can be used.

The software has been used to track data on people in hundreds of Chinese cities, and Zhou Jiangyong, the Communist Party secretary of the eastern tech hub of Hangzhou, says the app has become "loved so much that you cannot bear to part with it," adding it should become an "intimate health guardian," reports The New York Times, quoting an official announcement.

The concerns are not merely about snooping, but China's leaders have, for some time, been wanting to harvest troves of digital information on citizens to govern the nation more efficiently however, software bugs are also a concern, as errors that prove harmful could occur.

"Epidemic prevention and control need the support of big data technology, but this does not mean agencies and individuals can randomly collect citizens' information by borrowing the name of prevention and control," Li Sihui, a researcher at Huazhong University of Science and Technology in Wuhan, said in a recent commentary.

When signing up for the virus-tracking system, people in China submit personal information along with their travel and health service. 

The software then uses this to assign a color code of green, yellow, or red to indicate whether the holder is at risk of infection, and workers outside subways and other public places can stop anyone who does not have a green code on their phone app from entering. 

However, there has been confusion about how a green code is obtained, and as time passes, officials are talking about ranking citizens with a "personal health index, but it's not yet clear how that ranking would be used.

"Doesn't this brazenly violate privacy to surveil and discriminate against unhealthy people?" Wang Xin, a novelist, wrote on the social platform Weibo, where he has 2.5 million followers.

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